This invention relates to a method and apparatus for removing foreign objects from glass, and for separating glass into clear and colored pieces prior to recycling.
When glass is collected for recycling, foreign material, such as rocks, sticks, ceramics and other material, needs to be separated from the glass or the recycled glass will be contaminated. In addition, clear glass and colored glass must be separated from one another prior to recycling. Heretofore, this removal of foreign material and separation has been done by hand which is time-consuming and expensive.
The subject invention overcomes the foregoing problem by providing an apparatus which passes the unsorted material in a discrete array along a defined plane. An optical sensing device senses when an opaque particle passes through a first line defined in the plane and where the particle is located along the first line. A series of nozzles, which emit a jet of high velocity fluid, are located adjacent to the plane with the nozzles arranged along a second line that is parallel to and offset from the first line in the direction the particles are moving. An actuator is activated by the sensing device to cause fluid to be emitted from one of the nozzles when an opaque particle sensed by the sensing device passes through the second line and blow that particle out of the plane. A chute located behind the plane captures the particles blown out of the plane and separates them from the remainder of the particles.
In a preferred embodiment of the invention, the optical sensor is a source of high intensity light that is located on one side of the plane, and a multi-element machine vision camera that is located on the other side of the plane. The machine vision camera has a plurality of light-sensitive diodes that are aimed toward the light. The diodes generate an electrical signal and the strength of the signal of each diode varies proportional to the intensity of the light that reaches the diode. The signal from the diode is fed through a microprocessor, which causes the fluid to be emitted from the proper nozzle at the proper time to blow the opaque particle sensed by the diode out of the plane.
In the preferred embodiment, each nozzle is supplied fluid through one or more electrically operated valves. After sensing a reduced signal from one of the diodes, the microprocessor waits a predetermined time so that the particle drops between the first line and the second line, and then opens the valve associated with the nozzle that is most closely aligned with that diode. The nozzles are carried in a manifold, which also carries the valves and the conduits that interconnect the valves with the nozzles. The manifold can either be formed from a solid block or from a series of single nozzle-containing elements which are bolted together.
An optical filter can be placed between the particles and the camera if it is desired to sort pieces of colored glass from clear glass. The colored glass can be separated by using a filter that absorbs the wavelength of light emitted through the colored glass so that the glass particles appear opaque to the camera.
Accordingly, it is a principal objective of the subject invention to provide an apparatus which optically senses and removes opaque particles from a group of primarily transparent particles.
It is a further object of the present invention to provide such an apparatus which utilizes by a machine vision camera and high intensity source of light which shines through the particles toward the camera to sense the opaque particles.
It is a still further object of the subject invention to provide such an apparatus which uses a jet of high velocity fluid to remove the opaque particles from the plane.
It is yet a further object of the subject invention to provide such an apparatus in which there are a plurality of nozzles through which the jet of fluid can be emitted.
It is a still further object of the subject invention to provide such an apparatus in which fluid is fed to the nozzles through remotely controlled valves.
It is a further object of the subject invention to provide such an apparatus in which a microprocessor is used to open the appropriate valve at the proper time upon receiving a signal from the camera, so that a jet of fluid strikes a particular particle sensed by the camera.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.